• Accepted Paper

Probing SMEFT operators through tt‾tt‾ production with hypergraph neural networks at the LHC

Amir Subba and Sanmay Ganguly

Phys. Rev. D - Accepted 9 November, 2026

DOI: https://doi.org/10.1103/hk4q-htth

Abstract

The production of four top quarks (tt‾tt‾) at hadron colliders constitutes one of the rarest Standard Model (SM) processes accessible at the Large Hadron Collider (LHC) and provides a uniquely sensitive probe of the top-quark Yukawa coupling, of its possible CP structure, and of new physics encoded in four-heavy-fermion operators within the Standard Model Effective Field Theory (SMEFT) framework. We present a phenomenological study of tt‾tt‾ production in proton-proton collisions at s=13~TeV, using a Hyper-Graph Neural Network (H-GNN) to discriminate multilepton signal events from the dominant SM backgrounds viz. tt‾W, tt‾Z, tt‾H and tt‾VV processes. In the H-GNN architecture each event is represented as a hypergraph whose nodes correspond to reconstructed jets and leptons and whose hyperedges encode higher-order correlations among arbitrary subsets of these objects, allowing the network to learn the many-body kinematic structures that characterize the tt‾tt‾ final state. Combining same-sign di-lepton, tri-lepton, and four-lepton channels following a CMS-like event selection, the H-GNN attains an area under the ROC curve of 0.97 for the tt‾tt‾ signal and yields a statistical significance of Z=6.8 at ℒ=140~fb−1. We exploit the improved signal extraction to derive one-parameter 95% confidence level limits on the Wilson coefficients of the dimension-six operators 𝒪Φu, 𝒪tt(1), 𝒪qq(1), 𝒪qt(1), and 𝒪qt(8). We project the expected sensitivity at the HL-LHC integrated luminosities of 1000fb−1 and 3000fb−1 with 50% uncertainty on the background estimation. Finally, the sensitivity reach of H-GNN is compared to the SPANet and Particle Transformer baseline.

Export citation

Export citation

Choose format for download:

Download Citation

If the author has provided any supplemental materials with this article they will be available upon publication of the version of record.

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation